Tape laying apparatus and method

ABSTRACT

An automated tape head assembly for a multiple axis tape laying machine includes a tape supply reel and a tape compaction roller, and a chute. Tape passes from the supply reel, through the chute, to the tape compaction roller. The tape path and at least a portion of the chute are maintained substantially at a zero Gaussian curvature. The tape path and chute are curved to define a compliance loop that results from a substantially or partially unrestrained curved path between the supply reel and the compaction roller. This structure allows the compaction roller to shift laterally and vertically with respect to the supply reel while the supply reel is in a fixed position with respect to the tape head assembly generally. This structure also allows the compaction roller to roll, steer, and follow the fiber tape&#39;s natural path, all with significant independence from the supply reel.

This present application is a Continuation-In-Part of U.S. applicationSer. No. 11/570,516, which was filed on Oct. 14, 2008. U.S. applicationSer. No. 11/570,516 relies for priority on International PatentApplication No. PCT/IB2005/004184, filed on Jun. 10, 2005 and on U.S.Provisional Patent Application Ser. No. 60/581,948, filed on Jun. 22,2004. The contents of all three patent applications are incorporatedherein by reference. It is noted that U.S. patent application Ser. No.11/570,516 will issue as U.S. Pat. No. 7,836,931 on Nov. 23, 2010.

FIELD OF THE INVENTION

This application relates generally to machines that utilize a tape headto lay down composite strips on a surface and, more specifically tomachines that utilize a single tape head or multiple tape headssimultaneously to lay fiber tape onto a contoured surface or mandrel.

BACKGROUND OF THE INVENTION

Because of the nature of a tape, especially a stiff fiber tape, existingtape heads maintain a tape trajectory from the tape supply reel to thepoint of application onto a tool that does not allow the tape to movesignificantly out of a single plane. Existing tape head designs arecomprised of (1) a tape supply reel; (2) a tape driving and cuttingdevice; (3) a compaction roller or shoe that impresses the tape on tothe surface of the part in process; and (4) a tape backer take-up reel.In these prior implementations, these four items are mounted to a commonrigid structure such that their relative positions are fixed.

A number of designs have provided limited independent freedom of motionof the compaction roller with respect to the other three elementsdescribed above. Some of the prior art designs have passive compliancebuilt into the compaction roller or to the compaction roller rotationalshaft support, while others have a controlled position displacement bymeans of a motor or linear actuator. The designs with compliance of thecompaction roller provide this feature to allow tension control acrossthe tape width and allow limited steering of the tape or to impart acorrecting force to keep the tape tracking down the centerline of thecompaction roller.

One example provides for a tape head where the compaction roller canarticulate about an axis normal to the compaction roller tangent surfaceat the intended work surface contact point. This example also providesfor an accumulation of fiber tape such that the compaction roller canperform rapid motions to accommodate surface normal vector changeswithout having to respond with the entire tape head structureimmediately. However, the compaction roller work surface contact pointis fixed in the plane of the supply reel so that lateral displacementsof compaction roller require the entire structure to be displaced.Further, the necessary apparatus and control system requires numerouscontrols and actuators. The tape accumulation mechanism induces sharpbends in the tape and given the large dimensions of the entire assemblywould not be advantageous for a multiple tape head system where closelocation of adjacent tape heads may be necessary.

During tape lay-down a tape head assembly is steered and oriented tokeep the compaction roller's axis normal to the direction of travel and,normal to the work surface as the compaction roller lays tape along thetape center line. These motions require the entire mass and the entirevolume of this structure to be accelerated, moved and deceleratedimposing large demands for motor power and volume clearance around thetape head structure. The inertia is both translational and rotationalfor the tape head mass plus the rotational inertia of the supply reel.The supporting structure must also be larger and more massive toaccurately place the tape head relative to the tool or mandrel surface.The fact that the tape reel must be moved generally with the compactionroller limits the size of this reel and accordingly the amount of tapethat can be laid down on a part between tape re-loads.

Another example discloses a method to lay down fiber tape that utilizesmultiple tape heads each laying down a single fiber tape in coordinationwith the other tape heads and a rotating mandrel tool to fabricate asingle large fuselage section. This multiple head fiber tape machineprovides for a considerable reduction in the time required to fabricatea large fuselage section. However, since it utilizes a prior art tapehead design, the size of the fiber tape supply reel and itsreplenishment must be offset by the demands for space, as each tape headmust be articulated during the lay-up process and be accessible forreplenishment. The result is a very large heavy support structurerequired to maintain the tight positional tolerances between heads andlimited tape head packing density during operation, limiting the numberof heads that can be engaged in the lay-up process simultaneously.

A still further example exhibits a method and apparatus to provide atape head that does not have to be rotated at the termination of eachtape pass. This is accomplished by having two or more tape reels where,in one example, the two reels are at opposite sides of the compactionroller. While eliminating the need to perform the large rotationsbetween the termination of one pass and the start of another, thisdesign increases the overall weight and space required and therotational moment of inertia. A support structure and motion controlmeans would have to be larger and more powerful to accommodate this typeof design.

DEFINITIONS

Composite tape lay down heads are utilized to fabricate structuralcomponents that are comprised of multiple plies or lamina ofunidirectional fiber tapes either pre-impregnated with an adhesive resinor infused with an adhesive resin after lay-up assembly. The fabricationis carried out by adding successive strips of fiber tape onto a rigidcontoured support mold structure or contoured mandrel known as the toolwhich usually defines one surface of the finished part. Normally stripsof composite tape are laid down side-by-side until the surface of thepart is fully covered. One layer of generally parallel tape is known asa lamina. Successive lamina are laid down each on top of the precedinglamina, usually at a different angle of orientation to adjacent lamina.The surface upon which a tape is being applied is known as the worksurface. The finished part which is comprised of many lamina is known asa laminate.

When the lay-up procedure is completed, the finished part, while stillon the tool, is normally placed in a pressure and temperature controlledchamber known as an autoclave to aid in the consolidation of the partand cure the resin adhesive.

Each strip of fiber tape can be applied to the tool surface along anydirection. However, the path that the tape is to follow must not causekinking or buckling of the tape. This constraint is known as naturalpath and this type of path on a contoured surface will have continuouszero geodesic curvature.

In a number of applications such as parts of the aerodynamic surfaces asused on aerospace vehicles, some of the lamina cover only a portion ofthe part surface and these are usually associated with thicker sectionsof the laminate known as doublers where load concentrations are expectedto be higher. One or a number of tape heads are manipulated relative tothe surface of the tool by automatic machinery or a gantry system. Therelative motion between the tape head and the tool may include themotion of the tool, such as in the case of a rotating mandrel with acontoured surface. In the specific case of a resin impregnated fibertape, a wax paper tape known as a backer is usually releasably adheredto one side of the tape. The backer function is to prevent the tape fromadhering to itself while in roll form. This backer is relatively easy topeel away from the fiber tape as the backer is not utilized in the partbut is discarded.

It is important to distinguish between the type of tape head addressedby the present invention from other methods of laying down compositematerials such a fiber placement, yarn placement and filament winding. Afiber, a yarn or a filament are in general geometrically one dimensionaland can follow a straight line trajectory or a series of straight linetrajectories along their paths from their supply source to the point ofapplication, making turns if need be by means of pulleys or smooth rigidcurved guides.

A tape as manipulated in the present invention is a flat two dimensionalribbon with intrinsic geometric constraints. For example a flat tapedoes not allow twisting along a straight trajectory without inducingsignificant shear in the tape causing for example a striated fibroustape to splay, split apart or buckle. In general the vectors normal tothe tape surface at any two points along the tape's length must be inthe same plane unless the tape's path includes an untensioned spacecurve such that the zero Gaussian curvature of the tape be preserved.

SUMMARY OF THE INVENTION

The present invention solves the above problems by mechanicallyseparating a prior art tape head into two independent parts. Each partmay be articulated independently, or one with respect to the other. Thetape from a supply reel passes through the space between the twoindependent structures, taking a path that substantially maintains thezero Gaussian curvature of the tape, and allows smooth but substantiallyout of plane bending on the tape.

Unidirectional carbon fiber tapes are extremely stiff along theirlength, but are in general somewhat fragile due to the their filamentand uncured adhesive composition. Filament metrics must be respected asthe tape may splay or split if even small amounts of shear or bendingare imparted along the tape trajectory. If the Gaussian curvature of thetape is maintained near to zero then the tape will not be subjected todetrimental shear forces. Further, if the bending that the tape issubjected to is moderate, then the tape and backer will retain theirfiber and bond integrity. These tape path limitations may easily be metif the tape is allowed to travel in a substantially or partiallyunrestrained curved path between the supply reel and the compactionroller.

A substantially or partially unrestrained curved path may take the formof a C-shaped half circle, an S-shaped path, or may take the form ofpart of a helix. In all forms the tape's Gaussian curvature remainssubstantially close to zero. This curved path can be referred as acompliance loop.

A motorized feed roller located on a supply reel frame pulls tape fromthe supply reel and pushes the tape into the compliance loop. Anothermotorized feed roller located on the compaction roller structure pullstape from the compliance loop. These two motors must manage the amountof tape in the loop, and do so by combining feedback from velocity andposition sensors measuring the amount of tape passing through each endof the loop, and by sensing the loop depth by means of contact ornon-contact sensors such as ultrasonic or optical distance measuringsensors. This type of tape path curve has been used for many years bymotion picture cameras and projectors and is normally referred to asfilm loop or storage loop. The film loop provides for a small amount ofun-tensioned film between the supply reel and the frame exposuremechanism on the camera. A similar loop is also maintained between theframe exposure mechanism and the film take-up reel. The frame exposuremechanism requires very high accelerations and frequent starts and stopswhile both the supply and take-up reels are in smooth continuous motion.

The present invention takes an important step further by providing forrelative translational and rotational displacements to occur as the tapemoves through the compliance loop from the supply reel to the compactionroller. In general the present assembly provides for a significantdecrease in the mass of the parts of the tape head that must makenumerous position and track adjustments along a single tape course. Itnow becomes clear that maneuvering the compaction roller is much lessdemanding of the volume of space required as compared to the prior art.Further, the motion control system driving the compaction roller,comprised of motors, transmissions and amplifiers, can now besubstantially reduced in size and cost.

Another advantage of the present assembly is that it allows a very largetape supply reel to be used since the supply reel may be remote (forinstance at least about 10 to 100 times the width of the tape) and doesnot need to have its axis aligned with the compaction roller. In amulti-head system, the present invention allows for mounting a number ofsupply reel structures on a common frame, this frame can move relativeto the work surface. Each supply reel structure is provided with only asteering rotation of the supply reel axis with respect to the commonframe. Each supply reel would also have an associated compaction rollerstructure that could make translational and rotational orientationmovements relative to the common frame.

The present invention provides for the compaction roller to perform thefollowing motions independently of the supply reel:

Advance and retreat along the tape path sufficiently to allow tapecutting while the supply reel remains in translational motion relativeto the tool surface;

Roll about the tape centerline sufficiently to maintain the tool surfacenormal;

Pitch about the compaction roller contact point with the work surface,where the pitch axis of rotation would be parallel to the compactionroller shaft axis, to maintain the compaction roller structure normal tothe work surface;

Shift laterally and vertically so that the compaction roller canmaintain tape centerline and maintain natural path constraints asrequired while traveling over varying surface features on the tool; and

Shift laterally to allow the tape head access to a reasonable candidatetape centerline that may not be directly below the tape carriagecenterline.

All of these motions are on the order of two or three times the width ofthe tape and, for the motion normal to the tool or work surface,displacements of up to four or five times the width of the tape arepractical.

Other aspects of the invention will become apparent to those skilled inthe art after appreciating the details presented below.

BRIEF DESCRIPTION OF THE DRAWING(S)

The present invention is described in connection with the drawingappended hereto, in which:

FIG. 1 is a side elevation schematic view of a tape head assembly inaccordance with the present invention.

FIG. 2 is a front elevation schematic view of the tape head assemblyshown in FIG. 1.

FIG. 3A is a front elevation view of a pair of tape head assembliesidentical to the one shown in FIGS. 1 and 2.

FIG. 3B is a side elevation view a pair of tape head assemblies eachidentical to the one shown in FIGS. 1 and 2 in an alternativeconfiguration to that shown in FIG. 3A.

FIGS. 4A and 4B are top elevation and perspective views respectively ofa single supply wheel structure and compaction roll structure shown atthree successive locations as a tape head passes over a ramp on a worksurface.

FIGS. 5A and 5B are top elevation and perspective views respectively ofa supply rail structure and compaction roller structure of six tapeheads mounted on six locations on a single carriage simultaneouslyaddressing six separate tape courses on a work surface.

FIGS. 6A, 6B and 6C are top elevation, perspective and side viewsrespectively of a supply reel structure and compaction roller structureillustrating a single tape with an S-shaped tape path addressing alaterally displaced tape course.

FIGS. 7A and 7B are to plan and side elevation respectively of a supplyreel structure and compaction roller structure on a single tape headwith a helical-shaped tape path addressing a laterally displaced tapecourse.

FIG. 8 is a partial, side elevation schematic view of a tape headassembly in accordance with the present invention, illustrating anadditional embodiment contemplated by the present invention.

FIG. 9 is a graphic representation of the construction of a chutecontemplated in connection with the embodiment illustrated in FIG. 8.

DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

In one example, an automatic tape head assembly for a multiple axis tapelaying machine for depositing tape in courses upon a work surfacecomprises a tape supply reel and a tape compaction roller. The tapecompaction roller comprises a tape feed puller and a tape cutter. Thetape supply reel and tape compaction roller are independently movablerelative to the work surface and with respect to each other. The tapefed from the supply reel to the compaction roller and a tape travel paththere between is maintained at substantially zero Gaussian curvature.The tape travel path between the supply reel and the compaction rollermay be greater than a straight line between the supply reel andcompaction roller. The tape head assembly may further comprise a backerreel rotatable around a third axis and a backer travel path between thecompaction roller and the backer reel. The backer travel path may begreater than a straight line between the compaction roller and thebacker reel. The movement of the supply reel and compaction roller isaccomplished by independent positioning motors, and the positioningmotors may be controlled by a common controller. The supply reel mayunwind tape and feed it to the compaction roller in a continuous motion.The length of the tape travel path may vary during operation of the tapelaying machine. The tape travel path may have a generally C-shapedcurve, a generally S-shaped curve, or a generally helical-shaped curve.

The following example shown in the attached drawings is merely onealternative of the present invention. Of course those of skill in theart may take the teachings herein and develop further and additionalvariations based on the teachings herein.

Referring to FIG. 1 and FIG. 2, an example of an automated tape headassembly is shown. A tape supply reel 2, rotates on shaft 3, that issupported by the supply reel structure 4, pays out tape 25 (shown whenreel is full 5 and shown when reel is almost depleted 6), is guided overa roller 7, and descends to the motorized tape supply feed assembly 8.The feed assembly 8 pushes the tape 25 into the compliance loop 9.

The tape travel path between the feed assembly 8 (a portion of thesupply reel structure) and the feed assembly 110 (a portion of thecompaction roller structure) is shown as compliance loop 9. As shown,the tape travel path (compliance loop 9) has a C-shaped curve. The tapetravel path defines a substantially or partially unrestrained curve thatenables a substantially zero Gaussian curvature of the tape. A tapetravel path, in order to be substantially or partially unrestrained,must be greater than the distance defined by a straight line between asupply reel and a compaction roller. A tape travel path may also beS-shaped or define a generally helical-shaped curve.

Referring again to FIGS. 1 and 2, the tape 25 enters the compactionroller structure 11 and is guided into a motorized feed assembly 110where the backer tape 26 is removed and pushed into its uniquecompliance loop 13 by an associated motorized feed assembly 115. Thefiber tape 25, now separated from the backer tape 26 is pushed forwardby the pinch feed assembly 110, through the flying shear cutter assembly111 and under the compaction roller 112 where it is pressed adherentlyonto the work surface. The actual roller 112 can alternatively be a shoeor a presser shoe or foot. These alternative constructions are includedherein with respect to the term compaction roller.

The backer tape 26 passes through guides 10 to motorized puller assembly14 and then wound onto a motorized take-up reel 15 rotating on a shaft16. Paths 18 and 19 show the backer tape's path as it is wound onto thetake-up reel at the start 18 and finish 19 of winding.

The entire assembly is mounted on a single carriage 21 that can be movedby servo motor control (not shown) along linear bearings 22 fixed to asupport beam 20. The supply reel structure 2 is mounted on the carriage21 by means of a rotary bearing 34 whose rotation is positioned by aservo motor 32 and associated pinion and ring gear 33. The compactionroller structure 11 is moved relative to the supply reel structure 4 byfour servo motors—35, 36, 130 and 131.

The compaction roller structure 11 is positioned relative to the supplyreel structure 4 by the coordinated motion of the following four motorsand associated mechanical drive components: servo motor 35 is able totranslate the compaction roller structure support 12 parallel to the Zaxis 132, servo motor 36 is able to rotate the compaction rollerstructure support 12 about an axis indicated by 133, servo motor 36 isable to rotate the compaction roller structure 11 about another axisindicated by 130 and servo motor 131 is able to rotate the compactionroller structure 11 about the axis indicated by 134. Lastly the toolsurface 200 is able to translate along one axis controlled by a servomotor (not shown). The coordinated motion of all of these motors areable to position the compaction roller structure 11 relative to thesupply reel structure 4 and relative to the work surface 200 in alldegrees of freedom except pitch. The pitch rotation axis is defined asthe vector normal to both the tape course centerline and to the worksurface at any point along the tape centerline. Because of the moderatesurface contours of the tool experienced in this particular embodimentand to simplify the presentation, the pitch axis was not deemednecessary. And further, the axis required to translate the compactionroller structure in the direction along the tape path at the point ofcompaction roller contact with the work surface, is not required in thisembodiment to simplify the presentation and because the compactionroller structure contains a flying shear so that the tape head can cutwhile in motion relative to the work surface.

Suitable inverse kinematics calculations, well known in the art, thatutilize the desired tape course centerline, work surface normal vectorand the kinematics relationships of the all of the axis explained aboveare required to provide the command signals for each of the associatedmotors. The relative position of the compaction roller structure 11 withrespect to the supply reel structure 4 is further governed by the tapeand backer compliance loops 9 and 13 respectively.

A C-shaped compliance loop 9 (as shown) will require that there be asmall but significant steering angle offset between the plane normal tothe shaft of the supply reel and the plane of the normal to the shaft ofthe compaction roller when the compaction roller structure has to beeither positioned laterally (133 rotated) or rolled at an angle (134rotated) to the supply reel structure.

An S-shaped compliance loop does not require the small but significantangle as detailed above, but does impose a tighter bending radius on thetape. The compliance loops 9 and 13 for the tape 25 and the backer 26respectively are managed by their respective motorized feed assemblies110 and 14.

The supply reel 2 is managed by a servo motor 30 operating in torquemode so that it can rotate the reel to assist in its startup and apply aresisting torque to manage the tension on the tape and decelerate thereel. The backer reel 15 is managed in a similar manner as the supplyreel. However, the backer servo motor 31 is usually applying torque towind the tape.

FIGS. 3A and 3B show two different arrangements where two tape heads aremounted on to the same carriage 21, said carriage being able to movealong the Y axis beam, translating both tape head supply reel structures2 in fixed relation to one another along the Y axis. Each supply reelstructure may rotate independently relative to the carriage 21 about anaxis generally normal to the work surface that each head is to address.

When the beam is able to be controllably moved relative to the worksurface in the X direction, both of the tape heads are able to applytape simultaneously due to the fact that the compaction roller assemblyof each tape head can be positioned relative to its associated supplyreel structure. Each tape head is able to follow generally parallel, butsignificantly varying courses that, in this embodiment, are on the orderof two or three times the width of the tape.

Tape head proximity for fixedly mounting the heads to a common carriageis governed by avoidance of collisions between each of the tape heads orany appendage thereof during expected simultaneous movements.

Turning now to FIGS. 4A and 4B, there is shown a supply reel 2 andcompaction roller 112 as discussed in more detail earlier herein. Theadditional tape head structure has been removed for the sake ofdemonstrating the positional relationship between the supply reel 2 andthe compaction roller 112. In FIGS. 4A and 4B, the applied tape 201 hasbeen pressed onto the work surface 200. Three successive locations ofthe supply reel 2 versus the compaction roller 112 are shown as the tapehead passes over a ramp on the work surface 200. The supply reel 2 movesrelative to the work surface 200 at a fixed height along a straightline, while the compaction roller 112 structure makes path changes inthe transverse, roll and elevation directions. The tape travel path orcompliance loop 9 between the supply reel 2 and compaction roller 112shows a C-shape. The compliance loop 9 and the relative orientation ofthe supply reel 2 with the compaction roller 112 allow the compactionroller to enjoy substantial independent movement in relation to thesupply reel.

FIGS. 5A and 5B illustrate how an alternative tape head constructioncould operate. In these figures, the supply reel 2 are all fixed to asingle carriage (not shown) to allow the tape head to address sixseparate strips of applied tape 201 on the work surface 200. FIGS. 5Aand 5B demonstrate how this single tape head construction wouldconceptually operate in an efficient manner. The compliance loops 9facilitate the independent movement of the compaction rollers 112 withrespect to the respective supply reels 2.

FIGS. 6A, 6B and 6C demonstrate various views of a supply reel 2 andcompaction roller 112, and importantly, an S-shaped compliance loop 9.These figures illustrate how the applied tape 201 is adhered to the worksurface 200 by a compaction roller assembly as described. Thisalternative demonstrates the S-shaped compliance loop between the tapesupply 2 and the compaction roller 112. Of course, as with all of thetape travel path or compliance loop 9 illustrated herein, the size ofthe compliance loop may vary during operation or by design as a resultof the physical characteristics of the tape 25 that is being laid down.

FIGS. 7A and 7B illustrate a supply reel 2 and compaction roller 112 anda helical-shaped compliance loop 9 there between. In these figures, thesupply reel 2 is oriented such that the tape 25 will form a helicalcurve as it feeds from the reel 2 to the compaction roller 112. Thesize, curvature, and number of curves of the helical curve that may beformed will vary depending on the operation of the tape head assemblyand the type of tape that is being laid down.

Generally, with reference to all of FIGS. 4-7, the reference coordinateframe shows X, Y, Z as the right hand orthoganal axis, about which U, V,W are the rotational axis, also right hand oriented. The motion of thesupply reel 2 relative to the work surface 200 is in the positive Xdirection. Otherwise, the supply reel 2 maintains a fixed Y and Zposition where it is only allowed to rotate about the Z axis. On theother hand, the compaction roller 112 is allowed to articulate in atleast four degrees of freedom relative to its associated supply reel 2.The reel support structure has one degree of freedom—it is able torotate about the Z axis. The reel support structure can be fixed to aframe that either 1) is able to translate in the X-Y plan relative tothe work surface, 2) is able to translate in only the X or Y axis willthe work surface is able to translate along the other of the two axes (Xor Y), or 3) is stationary, where the work surface is able to translatein the X and Y directions.

FIG. 8 illustrates the relevant portion of another embodimentcontemplated for the present invention. In this illustration, the tapedispenser includes many of the same features and elements as the tapedispenser illustrated in FIG. 1. Accordingly, the same reference numbersare used. In addition, the discussion of the tape dispenser is largelythe same as discussed above and, therefore, is not repeated here.

In the embodiment illustrated in FIG. 8, a guide chute 90 has been addedaround the tape 25 in the compliance loop 9. The guide chute 90 includesan inner chute portion 91 and an outer chute portion 92, which arepositioned on either side of the compliance loop 9 in a spaced-apartrelationship thereto. The chute 90 is provided to guide the position ofthe tape 25 to ensure that the tape 25 remains in the appropriatedisposition as it travels to the motorized feed assembly 110 from themotorized tape supply feed assembly 8. It also protects the tape 25 asit travels within the compliance loop 9.

In this embodiment, the tape 25 in the compliance loop 9 retains itsC-shape and, thereby, maintains a travel path that defines asubstantially or partially unrestrained curve that enables asubstantially zero Gaussian curvature. As noted, the chute 90 assistswith maintaining the shape of the tape in the compliance loop 9. It alsoassists to discourage breakage of the tape 25, which may occur as aresult of external forces applied to the segment of the tape 25 in thecompliance loop 9.

The chute 90 may be made from two separate sheets of material that arepositioned on either side of the compliance loop 9, as illustrated. Thechute may be opened at the sides, meaning that it is possible to viewthe travel path of the tape 25 in the compliance loop 9 through thesides of the chute 90. Alternatively, the chute 90 may be entirelyclosed at its sides. In still one further contemplated embodiment, theouter chute portion 92 may be eliminated in whole or in part, creating aU-shaped channel around the tape 25.

It is contemplated that the chute 90 will be made from a flexiblematerial so that the chute 90 moves together with the motorized feedassembly 110 as the tape 25 is laid upon the tool surface 200. Materialsthat may comprise the chute 90 include, but are not limited to, steel,iron, iron-based alloys, aluminum, aluminum-based alloys, copper,copper-based alloys, plastics, rubbers, elastomeric materials, compositematerials, combinations of these substances, and the like.

It is contemplated that the chute 90 also may be made from a number ofsegments that are articulated with respect to one another. An exampleincludes, but is not limited to, a bike chain that includes multiplesegments that are articulated with respect to one another. With such aconstruction, the chute 90 offers considerable strength and rigidity,but also a considerable amount of flexibility.

FIG. 9 provides a graphic illustration of still one further contemplatedembodiment of the present invention. Here, it is contemplated that thechute 90 is made from a number of articulated sections 93 that areconnected, in an articulated manner, to one another.

In FIG. 9, two such articulated sections 93 are connected to one anothervia a hinge 94. The hinge 94 permits the articulated sections 93 to movewith respect to one another, thereby providing a chute 90 with anadjustable geometry. As should be apparent, for the chute 90 toencompass the tape 25 along the entirety of the compliance loop 9, aplurality of articulated sections 93 are expected to be connected to oneanother via a plurality of hinges 94.

In the embodiment illustrated in FIG. 9, it is contemplated that thehinges 94 will permit adjacent ones of the articulated sections 93 tomove with respect to one another. It is also contemplated, however, thatthe articulated sections 93 will be prevented from any other type ofmovement due to their construction. In other words, while thearticulated sections 93 may flex along the line 97, their motion wouldbe prohibited at the point where adjacent articulated sections 93 form astraight line (i.e., are aligned next to one another without any angulardisplacement).

With respect to the composition of the individual articulated sections93, any suitable material may be employed without departing from thescope of the present invention. As noted above, the materials mayinclude, but are not limited to, steel, iron, iron-based alloys,aluminum, aluminum-based alloys, copper, copper-based alloys, plastics,rubbers, elastomeric materials, composite materials, combinations ofthese substances, and the like.

It is contemplated that the hinges 94 will extend from one lateral edgeof each articulated section 93 to the other. However, this is notrequired to practice the present invention. The hinges 94 may besegmented across the lateral width 95 of the articulated sections 93,without departing from the scope of the present invention.

In connection with the articulated sections 93, a rectangular shape isillustrated. The rectangular shape is merely illustrative of oneembodiment contemplated for the present invention. As should beapparent, any suitable shape may be employed without departing from thescope of the present invention. In addition, the articulated sections 93may be U-shaped members that are connected to one another, leaving aportion of the tape exposed. In connection with this embodiment, it iscontemplated that the sides of the U-shaped portions may be slit inseveral locations, hereby permitting the bottom surfaces 96 to flex morefreely.

With respect to the embodiment illustrated in FIG. 9, the bottomsurfaces 96 of the articulated sections 93 are connected to one anothervia the hinge 94. The bottom surfaces 96 are understood to establish andmaintain the travel path that defines the substantially or partiallyunrestrained curve that enables a substantially zero Gaussian curvatureof the tape 25. In other words, the bottom surfaces 96 (i.e., theportion of the articulated sections 93 that comprise the chute 90) areresponsible, in this embodiment, for maintaining the tape 25 in theappropriate compliance curve 9 for purposes of the present invention.

As should also be apparent, while the chute 90 is discussed inconnection with the C-shaped travel path of the tape 25, the chute alsomay be employed where the tape 25 travels through an S-shaped curve or ahelical curve, among others.

While the invention has been described with reference to specificembodiments thereof, it will be understood that numerous variations,modifications and additional embodiments are possible, and all suchvariations, modifications, and embodiments are to be regarded as beingwithin the spirit and scope of the invention.

1. An automated tape head assembly for a multiple axis tape layingmachine for depositing tape in courses upon a work surface, the tapehead assembly comprising: a tape supply reel and a tape compactionroller; the tape compaction roller comprising a tape feed puller and atape cutter; the tape supply reel and tape compaction roller beingindependently moveable relative to the work surface and with respect toeach other; and a chute encompassing the tape in a tape travel path fromthe tape supply reel to the tape compaction roller; wherein the tapetravel path and at least a portion of the chute are maintained atsubstantially zero Gaussian curvature.
 2. An automated tape headassembly as described in claim 1, wherein the tape travel path betweenthe supply reel and the compaction roller is greater than a straightline between the supply reel and compaction roller.
 3. An automated tapehead assembly as described in claim 1, further comprising a backer reeland a backer travel path between the compaction roller and the backerreel, wherein the backer travel path is greater than a straight linebetween the compaction roller and the backer reel.
 4. An automated tapehead assembly as described in claim 1, wherein the movement of thesupply reel and compaction roller is accomplished by independentpositioning motors.
 5. An automated tape head assembly as described inclaim 4, wherein the positioning motors are controlled by a commoncontroller.
 6. An automated tape head assembly as described in claim 1,wherein the supply reel unwinds tape and feeds it to the compactionroller in a continuous motion.
 7. An automated tape head assembly asdescribed in claim 2, wherein the length of the tape travel path variesduring operation of the tape laying machine.
 8. An automated tape headassembly as described in claim 1, wherein the tape travel path betweenthe supply reel and the compaction roller has a generally C-shapedcurve.
 9. An automated tape head assembly as described in claim 1,wherein the tape travel path between the supply reel and the compactionroller has a generally S-shaped curve.
 10. An automated tape headassembly as described in claim 1, wherein the tape travel path betweenthe supply reel and the compaction roller has a generally helical-shapedcurve.
 11. An automated tape head assembly as described in claim 1,wherein the chute comprises: at least two articulated sections; and ahinge connecting the at least two articulated sections to one another.12. An automated tape head assembly as described in claim 11, wherein:the articulated sections define bottom surfaces, at least the bottomsurfaces of the articulated sections are connected to one another viathe hinge, and the bottom surfaces are maintained at substantially zeroGaussian curvature.
 13. An automated tape head assembly as described inclaim 11, wherein the articulated sections comprise at least onematerial selected from a group comprising steel, iron, iron-basedalloys, aluminum, aluminum-based alloys, copper, copper-based alloys,plastics, rubbers, elastomeric materials, composite materials, andcombinations thereof.
 14. An automated tape head assembly as describedin claim 1, wherein the chute comprises a flexible tube that surroundsthe tape travel path.